When manufacturing electrical devices (e.g., transistors) comprising graphene, the contact resistance between graphene and conventional contact electrodes made from metal exhibits high values that may limit the performance of such devices. The high contact resistance may be explained by two mechanisms. The term “electrical device” is meant to comprise electronic devices, as well, such as transistors, diodes, photodetectors, etc.
For metals that do not form a chemical bond with the graphene, the difference of the work functions of graphene (Φ=4.6 eV) and virtually all metals results in an alignment of the Fermi levels and a charge transfer.
For metals that form a chemical bond with graphene, the interaction between the π-electrons of the graphene and the d-electrons of the metals results in the formation of a bandgap.